NP Thundurus-T is indeed a great Wall breaker. I've been using:
Trait: Volt Absorb
Evs: 4Hp/252 Sp.Atk/252Spd
it's been one of the sweepers of my team. However the Speed loss is an issue. and Focus Sashe'd Mamoswines hinder it. But usually I leave mamo to something else on the Team.
Pokemon White FC: 2623 5521 3617